"Development of the human brain" Some of the anterior factors were inferred from the experiences carried out on experimental animals after altering the pattern of gyri and sulci during development (Rakic, 1981; Walsh, 1995). Rakic P. 1981. Developmental events leading to laminar and areal organization of the neocortex. In: Schmitt F.O. ed.The organization of the cerebral cortex. MIT Press. Cambridge. MA, p. 7-28. Rakic P., and Goldman-Rakic P.S. 1982. Development and modifiability of the cerebral cortex. Neuroc. Res. Progr. Bull., 20: 427-611 Walsh C., and Reid C. 1995. Cell lineage and patterns of migration in the developing cortex. In: Development of the cerebral cortex. Ciba Found. Symp, p.21-40. gyrification fissuration adult neurogenesis -> gyrification? notable loci: * Lateral sulcus, lat. sulcus lateralis with 3 branches: ramus ascendens, ramus anterior, and ramus posterior * Central sulcus, lat. sulcus centralis * Postcentral sulcus, lat. sulcus postcentralis * Precentral sulcus, lat. sulcus praecentralis * Cingulate sulcus, lat. sulcus cinguli Subcallosal sulcus, lat. sulcus corporis callosi * Superior frontal sulcus, lat. sulcus frontalis superior * Inferior frontal sulcus, lat. sulcus frontalis inferior Superior temporal sulcus, lat. sulcus temporalis superior Inferior temporal sulcus, lat. sulcus temporalis inferior Parieto-occipital sulcus, lat. sulcus parietoocipitalis Intraparietal sulcus, lat. sulcus intraparietalis Collateral sulcus, lat. sulcus collateralis Calcarine sulcus, lat. sulcus calcarinus `The surface of the cerebral cortex is folded in large mammals, such that more than two-thirds of the cortical surface is buried in the grooves, called "sulci."` "... neocortical architectonic fields. Relative variations in thickness or cell type (among other parameters) allow us to distinguish between different neocortical architectonic fields. The geometry of at least some of these fields seems to be related to the anatomy of the cortical folds, and, for example, layers in the upper part of the cortical ridges (called gyri) seem to be more clearly differentiated than in its deeper parts.[1]" [1] # ^ Welker, W. 1991. Why does the cerebral cortex fissures and folds? Cerebral Cortex, Vol 8b http://en.wikipedia.org/wiki/Sulcus_(neuroanatomy) # ^ Ono, Kubick, Abernathey, Atlas of the Cerebral Sulci, Thieme Medical Publishers, 1990. ISBN 0-86577-362-9. ISBN 3-13-732101-8. "Mammals that have smooth-surfaced or nonconvoluted brains are called lissencephalics and those that have folded or convoluted brains gyrencephalics" gyrencephalics - mammals that have folded/convoluted brains lissencephalics - mammals that have smooth/nonconvoluted brains (pachygyria) microgyria polymicrogyria - "It is also characterized by shallow sulci, a slightly thicker cortex, neuronal heterotopia and enlarged ventricles. When many of these small folds are packed tightly together, PMG may resemble pachygyria (a few "thick folds" - a mild form of lissencephaly)." In humans, cerebral convolutions appear at about 5 months and take at least into the first year after birth to fully develop.[5][2][3] [5] # ^ Caviness VS Jr. (1975). Mechanical model of brain convolutional development. Science. 189(4196):18-21. PMID 1135626 [2] # ^ a b Hofman MA. (1985). Size and shape of the cerebral cortex in mammals. I. The cortical surface. Brain Behav Evol. 27(1):28-40. PMID 3836731 [3] # ^ a b Hofman MA. (1989).On the evolution and geometry of the brain in mammals. Prog Neurobiol.32(2):137-58. PMID 2645619 increased left prefrontal cortical convolutions increased left prefrontal cortical folding increased left prefrontal cortex convolutions increased left prefrontal cortex gyrification increased right prefrontal cortex gyrification in schizophrenia Brains, intelligence, and how they don't correlate http://dml.cmnh.org/2001May/msg00866.html - "Another common argument says that not absolute or relative brain size matters but the size of the cortex respectively the number of its convolutions. We humans are indeed particularly proud of our big and highly convoluted neocortex, and there is a widespread assumption that the size of the human cortex as well as the number of its convolutions are unique. This, too, is an error. As [cool] figures [...] show, whales, dolphins, and also elephants have a much bigger neocortex with many more convolutions than our brain. If one takes a closer look at the affair it becomes apparent that cortex size is not, as many believe, determined by some extreme evolutionary selection factor for intelligence, but simply by brain size: Big brains have big cortices that vault themselves simply for architectonical reasons. Therefore whales, dolphins, and elephants have a much bigger and more convoluted cortex than we." It's just another allometry.